Evaluation of PEEP and prone positioning in early COVID-19 ARDS.

Background: In face of the Coronavirus Disease (COVID)-19 pandemic, best practice for mechanical ventilation in COVID-19 associated Acute Respiratory Distress Syndrome (ARDS) is intensely debated. Specifically, the rationale for high positive end-expiratory pressure (PEEP) and prone positioning in early COVID-19 ARDS has been questioned.
Methods: The first 23 consecutive patients with COVID-19 associated respiratory failure transferred to a single ICU were assessed. Eight were excluded: five were not invasively ventilated and three received veno-venous ECMO support. The remaining 15 were assessed over the first 15 days of mechanical ventilation. Best PEEP was defined by maximal oxygenation and was determined by structured decremental PEEP trials comprising the monitoring of oxygenation, airway pressures and trans-pulmonary pressures. In nine patients the impact of prone positioning on oxygenation was investigated. Additionally, the effects of high PEEP and prone positioning on pulmonary opacities in serial chest x-rays were determined by applying a semiquantitative scoring-system. This investigation is part of the prospective observational PA-COVID-19 study.
Findings: Patients responded to initiation of invasive high PEEP ventilation with markedly improved oxygenation, which was accompanied by reduced pulmonary opacities within 6 h of mechanical ventilation. Decremental PEEP trials confirmed the need for high PEEP (17.9 (SD ± 3.9) mbar) for optimal oxygenation, while driving pressures remained low. Prone positioning substantially increased oxygenation ( p <0.01).
Interpretation: In early COVID-19 ARDS, substantial PEEP values were required for optimizing oxygenation. Pulmonary opacities resolved during mechanical ventilation with high PEEP suggesting recruitment of lung volume.
Funding: German Research Foundation, German Federal Ministry of Education and Research.
Competing Interests: MD is European Society of Radiology (ESR) Research Chair (2019–2022) and the opinions expressed in this publication are the author's own and do not represent the view of ESR. MD gives lectures for Canon, and Guerbet, and holds hands-on cardiac CT courses (www.ct-kurs.de). He is Editor of Cardiac CT (Springer Nature). He has institutional research agreements with Siemens, General Electric, Philips, Canon, and has a patent on fractal analysis of perfusion imaging (jointly with Florian Michallek, PCT/EP2016/071551). All other authors declare no conflict of interest.
(© 2020 The Author(s).)